In most common wireless headphones, the communication between the headphone and an audio frequency source (for example, a mobile phone) is maintained by only one radio frequency (RF) receiver. No electric wire is provided between a left earbud and a right earbud of a pair of full wireless headphones, and a stereo effect between a left ear and a right ear may be synchronized by means of a wireless communication channel. In order to realize a full wireless headphone effect, an individual wireless receiver is necessary for each earbud. Most commonly, the full wireless headphone is implemented through two Bluetooth communication lines.
In order to ensure smooth communication between the left earbud and the right earbud, apparently, it is possible to make an antenna away from a human skin as far as possible, to furthest reduce the attenuation caused by a human body. A relatively large antenna may also improve an RF transmission efficiency, and offset the attenuation by the human body. Neither of the two solutions matches a profile of a product with an auricle. The common design method for a full wireless product is to make the headphone not close to the auricles, and place an electronic product in a relatively large product. However, as for a relatively large product, its size goes against an idea of miniaturization, never realizing a product with a light weight and an in-ear-fit application. Another solution for designing the full wireless headphone is an over-ear design where the antenna is placed inside an over-ear headphone. With such a design, the antenna may be easily insulated from the human skin. However, such a structure is too large to be suitable for an in-ear device.
The Chinese invention No. CN105792049A discloses a pure wireless headphone through adoption of an optimum monopole antenna which is configured to build an appropriate RF communication link between an in-ear main receiver and an in-ear auxiliary receiver on head. Meanwhile, the optimum monopole antenna is also able to maintain an appropriate RF communication link between the main receiver and a mobile phone, and is suitable for generating an RF communication link and an RF creeping wave to be coupled with the human skin, so as to ensure the omni-directional radiation of the antenna. However, experiments show that this invention has the following defects that: 1) the monopole antenna cannot ensure the optimum antenna radiation due to a blocking effect by a human face; 2) a connection between a main device and an auxiliary device is not firm; 3) a radiation direction is not parallel with a human face profile, thereby causing a relatively small RF range and relatively poor stability of the wireless connection.